This application claims the priority of German Application No. 197 49 587.7, filed Nov. 10, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and a device for influencing an impression which is subjectively perceived by an occupant of a vehicle, in particular of a passenger car, when the vehicle is being operated. A known method of this type is described in U.S. Pat. No. 5,332,061, the specification of which is incorporated herein by reference.
U.S. Pat. No. 5,332,061 discloses a method for suppressing vibrations which are induced in the body of a vehicle, as well as disclosing a corresponding vehicle in which the method is practiced. The respective induced vibrations originate from the engine and are transmitted to the points where the engine connects to the body of a vehicle. In order to suppress these vibrations, the vehicle has shakers, that is to say mechanical vibration exciters, which are arranged in the region of at least a number of connection points between the engine and the body of the vehicle. When the engine is operated, the shakers are excited as a function of the rotational speed of the engine at the resonant frequencies in antiphase with respect to vibrations coming from the engine, thus causing the transmission of the induced vibrations to be at least attenuated. The corresponding frequencies and their amplitudes for the secondary oscillations are obtained here from a previously written data field.
U.S. Pat. No. 5,434,783 A1 discloses a vehicle in which the background noise which can be heard within a passenger cell is influenced by sound waves. In addition to normal loudspeakers, use is also made here of a piezoelement which excites at least parts of the vehicle body to oscillate and thus influences it so as to emit sound waves; i.e. the piezoelement acts like a coil of a loudspeaker, while the vehicle body represents the oscillating diaphragm. The previously known method and device make it possible to improve the subjective sensation within the passenger cell.
The object of the invention is therefore to develop further the basic method and device in such a way that the subjective sensation of impressions is improved upon.
This and other objects are achieved by a method for influencing an impression which is subjectively perceived by an occupant of a vehicle, in particular of a passenger car, when the vehicle is operating, in which primary oscillations are produced and determined when the vehicle is operating. Furthermore, data which are acquired for secondary oscillations are artificially generated from the primary oscillations. Vibration oscillations which can be subjectively perceived through the human body are generated artificially as at least part of the secondary oscillations. At least one of the components of the vehicle body is excited using the vibration oscillations. The vibration oscillations are placed in an interference relationship with at least some of the frequencies of the primary oscillations, and at least certain frequencies of the primary oscillations which are produced while the vehicle is operating are changed by the interference. The steering wheel is excited so as to undergo mechanical vibration oscillations. The vibration oscillations of the steering wheel are those subjected to interference by the primary oscillations. A device is also provided for influencing an impression which is subjectively perceived by an occupant of a vehicle, in particular of a passenger car, when the vehicle is being operated, using oscillation exciters with which secondary oscillations can be artificially generated when the vehicle is being operated. In this case, at least certain frequencies are reduced or, if appropriate, also increased due to interference of the secondary oscillations with the primary oscillations produced while the vehicle is operating. A vibration exciter which induces vibration oscillations which can be perceived through the human body is assigned to the steering wheel. The steering wheel can therefore be excited to undergo vibration oscillations which can be perceived through the human body, using the oscillation exciter.
By influencing the vibrations perceived by the body of the vehicle occupant or occupants it is possible to improve in a relatively simple way not only the acoustically perceived subjective impression but also the overall impression. Vibrations perceived by the body are understood to be oscillations which a person notices, for example, as a result of shaking of the steering wheel, rocking or shaking of the seat etc. The steering wheel is also, in particular, advantageously assigned an oscillation exciter which excites vibration oscillations. It is particularly surprising here that certain impressions cannot be sensed at all unless corresponding vibration oscillations are excited in the steering wheel. If, on the other hand, the steering wheel is not excited, a completely different impression is produced. As a result of the fact that the vibration oscillations which act at least in part as counter-oscillations are induced in the region of at least the driver's seat and/or of the steering wheel, the results of the interference act precisely on one particular vehicle occupant. Their influence on the vehicle body is at most small so that the driving safety of the vehicle is not affected, for which reason it is also impossible for it to be adversely influenced. The generation of the vibration oscillations can take place in a way which is analagous to the method known from the field of active-noise reduction so that more precise details on this are not necessary. The improvement can include amplifying certain frequencies or frequency patterns or, in particular, suppressing them, and relates not only to the vibrations which can be perceived through the human body and are noticed by the driver and/or the vehicle occupants. Here, frequency pattern is understood to be a large number of the frequencies which have, for example, a specific envelope curve or also a specific Fourier spectrum, for example. The respective frequencies may be due, for example, to the engine, the chassis, the tires, the condition of the road or else to the activation of the windscreen wiper or fan.
For a simple embodiment of the invention, it may be sufficient to influence satisfactorily the subjectively perceived vibrations if frequencies up to 150 Hz are gated out, for example, by means of a low-pass filter, from the airborne sound signal which can be recorded, for example, by means of one or more microphones. The vibration oscillations are then generated with the gated-out low-frequency component. The signals which cause the vibration oscillations are used, in particular, to actuate oscillation exciters which are arranged in the steering gear and/or on the seat rail. Additionally, it is particularly advantageous to actuate a low-frequency loudspeaker with modified signals. The speaker then covers the low-frequency component of the acoustic airborne sound.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.